I have a strange sound of moving parts coming from behind my driver seat or inside my driver door, cant tell precisely.
It sounds as if it is a bolt or a coin moving/rolling from side to side when I stop the car or start accelerate it. Looked inside the car holder area in the door and in the big door compartment, all are empty. Looked behind my seat, and everything looks normal. anybody have any experience where to look for that annoying moving part?

We had the same issue. Started at about 2000 miles and lasted a month. Has not returned but it was annoying. Just as you described, something rolling forward and back. I wish I knew the case in case it returns.

Found it today thanks to you guys,
It was a rachet screw bit left by the mechanic in the area of the compartment under the driver seat, BUT not inside the compartment, it was between that compartment and the door, there is a small and deep gap where you can actually see the car metal sheet, shove my hand to that narrow gap and found it. Amazing!!!